Cassette air conditioners are one of the main types of inverter split systems. They are usually installed on the ceiling and use cooling fans to circulate air. Cassette air Conditioners work by using a fan to move air around the unit. Cassette air conditioners work like other wall-mounted split system units. They use a compressor to cool the air and a fan to circulate the air.The difference is that the cassette systems are mounted in the ceiling and not on the wall, and the powerful cooling of the cassette unit, along with its central (more or less) placement in the ceiling, makes it very suitable for large living.